Mangilao Village, Guam

University of Guam

www.uog.edu
Mangilao Village, Guam

University of Guam is a four-year land-grant institution, located in the village of Mangilao on the island of Guam in the Western Pacific Ocean. It is accredited by the Western Association of Schools and Colleges and offers thirty-four degree programs at the undergraduate level and eleven master’s level programs.Of the University’s 3,387 students, 91% are of Asian-Pacific Islander ethnicity, and nearly 69% are full-time . A full-time faculty of about 180 supports the University’s mission of "Ina, Diskubre, Setbe"— which translates to "To Enlighten, to Discover, to Serve." Wikipedia.


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A Scripps Institution of Oceanography at the University of California San Diego-led research team discovered for the first time that a common marine sponge hosts bacteria that specialize in the production of toxic compounds nearly identical to man-made fire retardants. The new findings put the research team one step closer to unraveling the mystery of this powerful group of chemical compounds, known as polybrominated diphenyl ethers (PBDEs), in the marine environment. PBDEs are a subgroup of brominated flame retardants that are combined into foam, textiles, and electronics to raise the temperature at which the products will burn. These man-made industrial chemicals are powerful endocrine disruptors that mimic the activity of the human body's most active thyroid hormone. Vinayak Agarwal, a postdoctoral researcher at Scripps, picked up a cold case first started nearly 50 years ago by Scripps chemist John Faulkner, an early pioneer in the study of natural products from the sea, to continue the investigation into the source of these toxic compounds that are found in large quantities in the world’s oceans. “For the first time we were able to conclusively show that genes and enzymes produced in bacteria from sponges are responsible for the production of these compounds toxic to humans,” said Agarwal, co-first author of the paper along with Scripps PhD student Jessica Blanton. The study was part of the National Science Foundation (NSF)/ National Institute of Environmental Health Sciences (NIEHS)-funded Center for Oceans and Human Health research being conducted at Scripps. In 2014, Agarwal and colleagues at Scripps Oceanography were the first to discover that unrelated free-living marine bacteria produce these fire retardant compounds naturally, albeit in very small quantities. In this new study, the researchers employed two modern-day techniques—genome “mining” pioneered by Scripps marine chemist Brad Moore and an environmental DNA sequencing approach pioneered by Scripps biologist Eric Allen—to take the investigation a step further and identify the specific genes and enzymes involved in the overproduction of the toxic molecules in sponges. Marine sponges obtain food and oxygen by filtering seawater through the pores and channels in their bodies. This constant water flow means that these immobile animals host many bacteria, viruses, and fungi in their complex microbiomes. The research team collected 18 sponge samples for the study during two research expeditions to Guam. They then isolated the various components of this complex mixture of organisms from the sponge’s tissues to identify the specific genes and enzymes that code for the production of PBDEs. “For many years scientists were finding clues that suggested nature was making these compounds,” said Bradley Moore, a professor at the Scripps Center of Marine Biotechnology and Biomedicine and the Skaggs School of Pharmacy and Pharmaceutical Sciences at UC San Diego, and a senior author of the study. “Now that we understand how they are produced in the marine environment, we are exploring why they exist, and the human health concerns associated with them.” Moore’s genome "mining" approach along with Allen’s metagenomic sequencing gives scientists a way to connect the natural chemicals produced by organisms back to the enzymes that construct them. The study, which appears on the cover of the May issue of the journal Nature Chemical Biology, was a unique collaboration among chemists and biologists at UC San Diego and elsewhere. “This study is a powerful combination of chemical, biological and environmental research,” said Henrietta Edmonds of the NSF’s Division of Ocean Sciences, which supported the research. “It has the potential to help us understand the production, fate and health consequences of natural and pollutant compounds in the marine environment.” “We care about naturally produced PBDEs because they end up in the food chain,” said Frederick Tyson, Ph.D., of the NIEHS, which helped to fund the research. “Preliminary data from this research team suggest that some naturally occurring PDBEs may be even more toxic than those that are man-made, so we need to develop a better understanding of these compounds.” These ocean-dwelling microbes have been found in habitats as diverse as sea grasses, corals and whales. The next step of the investigation for the researchers is to mine the genes and enzymes in other marine hosts to find out what other organisms are making similar toxic compounds and why. Co-authors from Scripps Oceanography include Sheila Podell, Michelle Schorn, Julia Busch, and Paul Jensen. Researchers Arnaud Taton and James Golden from UC San Diego’s Division of Biological Sciences, Jason Biggs from University of Guam’s Marine Laboratory, Zhenjian Lin and Eric Schmidt from the University of Utah, and Valerie Paul from the Smithsonian Marine Station also contributed to the study. Funding for the research was provided through: National Science Foundation grants OCE-1313747, DGE-1144086, IOS-1120113, MCB-1149552; National Institutes of Health grants P01-ES021921, K99-ES026620, R01-GM107557, R01-CA172310, S10-OD010640; the U.S. Department of Energy grant DE-EE0003373; and a Helen Hay Whitney Foundation postdoctoral fellowship.


News Article | May 11, 2017
Site: www.eurekalert.org

A Scripps Institution of Oceanography at the University of California San Diego-led research team discovered for the first time that a common marine sponge hosts bacteria that specialize in the production of toxic compounds nearly identical to man-made fire retardants. The new findings put the research team one step closer to unraveling the mystery of this powerful group of chemical compounds, known as polybrominated diphenyl ethers (PBDEs), in the marine environment. PBDEs are a subgroup of brominated flame retardants that are combined into foam, textiles, and electronics to raise the temperature at which the products will burn. These man-made industrial chemicals are powerful endocrine disruptors that mimic the activity of the human body's most active thyroid hormone. Vinayak Agarwal, a postdoctoral researcher at Scripps, picked up a cold case first started nearly 50 years ago by Scripps chemist John Faulkner, an early pioneer in the study of natural products from the sea, to continue the investigation into the source of these toxic compounds that are found in large quantities in the world's oceans. "For the first time we were able to conclusively show that genes and enzymes produced in bacteria from sponges are responsible for the production of these compounds toxic to humans," said Agarwal, co-first author of the paper along with Scripps PhD student Jessica Blanton. The study was part of the National Science Foundation (NSF)/ National Institute of Environmental Health Sciences (NIEHS)-funded Center for Oceans and Human Health research being conducted at Scripps. In 2014, Agarwal and colleagues at Scripps Oceanography were the first to discover that unrelated free-living marine bacteria produce these fire retardant compounds naturally, albeit in very small quantities. In this new study, the researchers employed two modern-day techniques--genome "mining" pioneered by Scripps marine chemist Brad Moore and an environmental DNA sequencing approach pioneered by Scripps biologist Eric Allen--to take the investigation a step further and identify the specific genes and enzymes involved in the overproduction of the toxic molecules in sponges. Marine sponges obtain food and oxygen by filtering seawater through the pores and channels in their bodies. This constant water flow means that these immobile animals host many bacteria, viruses, and fungi in their complex microbiomes. The research team collected 18 sponge samples for the study during two research expeditions to Guam. They then isolated the various components of this complex mixture of organisms from the sponge's tissues to identify the specific genes and enzymes that code for the production of PBDEs. "For many years scientists were finding clues that suggested nature was making these compounds," said Bradley Moore, a professor at the Scripps Center of Marine Biotechnology and Biomedicine and the Skaggs School of Pharmacy and Pharmaceutical Sciences at UC San Diego, and a senior author of the study. "Now that we understand how they are produced in the marine environment, we are exploring why they exist, and the human health concerns associated with them." Moore's genome "mining" approach along with Allen's metagenomic sequencing gives scientists a way to connect the natural chemicals produced by organisms back to the enzymes that construct them. The study, which appears on the cover of the May issue of the journal Nature Chemical Biology, was a unique collaboration among chemists and biologists at UC San Diego and elsewhere. "This study is a powerful combination of chemical, biological and environmental research," said Henrietta Edmonds of the NSF's Division of Ocean Sciences, which supported the research. "It has the potential to help us understand the production, fate and health consequences of natural and pollutant compounds in the marine environment." "We care about naturally produced PBDEs because they end up in the food chain," said Frederick Tyson, Ph.D., of the NIEHS, which helped to fund the research. "Preliminary data from this research team suggest that some naturally occurring PDBEs may be even more toxic than those that are man-made, so we need to develop a better understanding of these compounds." These ocean-dwelling microbes have been found in habitats as diverse as sea grasses, corals and whales. The next step of the investigation for the researchers is to mine the genes and enzymes in other marine hosts to find out what other organisms are making similar toxic compounds and why. Co-authors from Scripps Oceanography include Sheila Podell, Michelle Schorn, Julia Busch, and Paul Jensen. Researchers Arnaud Taton and James Golden from UC San Diego's Division of Biological Sciences, Jason Biggs from University of Guam's Marine Laboratory, Zhenjian Lin and Eric Schmidt from the University of Utah, and Valerie Paul from the Smithsonian Marine Station also contributed to the study. Funding for the research was provided through: National Science Foundation grants OCE-1313747, DGE-1144086, IOS-1120113, MCB-1149552; National Institutes of Health grants P01-ES021921, K99-ES026620, R01-GM107557, R01-CA172310, S10-OD010640; the U.S. Department of Energy grant DE-EE0003373; and a Helen Hay Whitney Foundation postdoctoral fellowship. Scripps Institution of Oceanography at the University of California, San Diego, is one of the oldest, largest, and most important centers for global science research and education in the world. Now in its second century of discovery, the scientific scope of the institution has grown to include biological, physical, chemical, geological, geophysical, and atmospheric studies of the earth as a system. Hundreds of research programs covering a wide range of scientific areas are under way today on every continent and in every ocean. The institution has a staff of more than 1,400 and annual expenditures of approximately $195 million from federal, state, and private sources. Scripps operates oceanographic research vessels recognized worldwide for their outstanding capabilities. Equipped with innovative instruments for ocean exploration, these ships constitute mobile laboratories and observatories that serve students and researchers from institutions throughout the world. Birch Aquarium at Scripps serves as the interpretive center of the institution and showcases Scripps research and a diverse array of marine life through exhibits and programming for more than 430,000 visitors each year. Learn more at scripps.ucsd.edu and follow us at: Facebook | Twitter | Instagram. At the University of California San Diego, we constantly push boundaries and challenge expectations. Established in 1960, UC San Diego has been shaped by exceptional scholars who aren't afraid to take risks and redefine conventional wisdom. Today, as one of the top 15 research universities in the world, we are driving innovation and change to advance society, propel economic growth, and make our world a better place. Learn more at http://www. .


A Scripps Institution of Oceanography at the University of California San Diego-led research team discovered for the first time that a common marine sponge hosts bacteria that specialize in the production of toxic compounds nearly identical to man-made fire retardants. The new findings put the research team one step closer to unraveling the mystery of this powerful group of chemical compounds, known as polybrominated diphenyl ethers (PBDEs), in the marine environment. PBDEs are a subgroup of brominated flame retardants that are combined into foam, textiles, and electronics to raise the temperature at which the products will burn. These man-made industrial chemicals are powerful endocrine disruptors that mimic the activity of the human body's most active thyroid hormone. Vinayak Agarwal, a postdoctoral researcher at Scripps, picked up a cold case first started nearly 50 years ago by Scripps chemist John Faulkner, an early pioneer in the study of natural products from the sea, to continue the investigation into the source of these toxic compounds that are found in large quantities in the world’s oceans. “For the first time we were able to conclusively show that genes and enzymes produced in bacteria from sponges are responsible for the production of these compounds toxic to humans,” said Agarwal, co-first author of the paper along with Scripps PhD student Jessica Blanton. The study was part of the National Science Foundation (NSF)/ National Institute of Environmental Health Sciences (NIEHS)-funded Center for Oceans and Human Health research being conducted at Scripps. In 2014, Agarwal and colleagues at Scripps Oceanography were the first to discover that unrelated free-living marine bacteria produce these fire retardant compounds naturally, albeit in very small quantities. In this new study, the researchers employed two modern-day techniques—genome “mining” pioneered by Scripps marine chemist Brad Moore and an environmental DNA sequencing approach pioneered by Scripps biologist Eric Allen—to take the investigation a step further and identify the specific genes and enzymes involved in the overproduction of the toxic molecules in sponges. Marine sponges obtain food and oxygen by filtering seawater through the pores and channels in their bodies. This constant water flow means that these immobile animals host many bacteria, viruses, and fungi in their complex microbiomes. The research team collected 18 sponge samples for the study during two research expeditions to Guam. They then isolated the various components of this complex mixture of organisms from the sponge’s tissues to identify the specific genes and enzymes that code for the production of PBDEs. “For many years scientists were finding clues that suggested nature was making these compounds,” said Bradley Moore, a professor at the Scripps Center of Marine Biotechnology and Biomedicine and the Skaggs School of Pharmacy and Pharmaceutical Sciences at UC San Diego, and a senior author of the study. “Now that we understand how they are produced in the marine environment, we are exploring why they exist, and the human health concerns associated with them.” Moore’s genome "mining" approach along with Allen’s metagenomic sequencing gives scientists a way to connect the natural chemicals produced by organisms back to the enzymes that construct them. The study, which appears on the cover of the May issue of the journal Nature Chemical Biology, was a unique collaboration among chemists and biologists at UC San Diego and elsewhere. “This study is a powerful combination of chemical, biological and environmental research,” said Henrietta Edmonds of the NSF’s Division of Ocean Sciences, which supported the research. “It has the potential to help us understand the production, fate and health consequences of natural and pollutant compounds in the marine environment.” “We care about naturally produced PBDEs because they end up in the food chain,” said Frederick Tyson, Ph.D., of the NIEHS, which helped to fund the research. “Preliminary data from this research team suggest that some naturally occurring PDBEs may be even more toxic than those that are man-made, so we need to develop a better understanding of these compounds.” These ocean-dwelling microbes have been found in habitats as diverse as sea grasses, corals and whales. The next step of the investigation for the researchers is to mine the genes and enzymes in other marine hosts to find out what other organisms are making similar toxic compounds and why. Co-authors from Scripps Oceanography include Sheila Podell, Michelle Schorn, Julia Busch, and Paul Jensen. Researchers Arnaud Taton and James Golden from UC San Diego’s Division of Biological Sciences, Jason Biggs from University of Guam’s Marine Laboratory, Zhenjian Lin and Eric Schmidt from the University of Utah, and Valerie Paul from the Smithsonian Marine Station also contributed to the study. Funding for the research was provided through: National Science Foundation grants OCE-1313747, DGE-1144086, IOS-1120113, MCB-1149552; National Institutes of Health grants P01-ES021921, K99-ES026620, R01-GM107557, R01-CA172310, S10-OD010640; the U.S. Department of Energy grant DE-EE0003373; and a Helen Hay Whitney Foundation postdoctoral fellowship.


News Article | May 2, 2017
Site: www.eurekalert.org

Many rare tropical tree species are restricted to a small, endemic range with very few remaining reproductive individuals. These species suffer from many threats. Conservation agencies often attempt to rebuild the population within the known endemic range of these endangered trees. This desire to rebuild robust populations of rare trees is constrained by the need to protect any remaining adult trees. Conservation permitting agencies generally limit the number of seeds and cuttings that can be taken by conservation practitioners. The unfortunate result of these justifiable restrictions is that very few new propagules can be produced every year for the purpose of rebuilding the population. Serianthes nelsonii is found on two small islands in the Mariana Island Archipelago, and the population has declined to one individual on one of those islands. The recovery plan for this species calls for the propagation of more than 4,000 transplants for out-planting into several population sties. Recent propagation research conducted at the University of Guam has opened up new protocols that may greatly expand the number of propagules that can be produced every year in support of these goals. The results were published in the current issue of the journal Tropical Conservation Science. "The most successful propagation techniques vary from species to species," said author Thomas Marler. "This is especially true for woody tree species, and dedicated propagation trials are needed for each species." The new knowledge allows conservation nurseries to capitalize on the fact that specimens growing in a nursery can be used as a source for an unrestricted number of new propagules. Marler also illuminates an approach that can exploit the fresh stem tissue that is dislodged during tropical cyclones. Indeed, the western Pacific Ocean has the distinction of being the most active tropical cyclone region globally. These violent storms defoliate and dislodge branches, leaving a pulse of green litter on the forest floor. The green stem tissue found among the copious amounts of leaf litter immediately following one these storms would not fall under the permitting restrictions of how many cuttings can be taken from the trees. Conservation nurseries may maintain a collection of container-grown plants throughout each annual tropical cyclone season, ready to serve as rootstocks for the creation of grafted plants using suitable green stem tissue collected from the forest floor following a tropical cyclone. The case study is an example of how non-destructive horticulture research can be implemented on endangered species nursery plants as a means of improving species recovery protocols. Conservation funding agencies would benefit from contracting competent horticultural researchers to manage conservation nurseries.


This desire to rebuild robust populations of rare trees is constrained by the need to protect any remaining adult trees. Conservation permitting agencies generally limit the number of seeds and cuttings that can be taken by conservation practitioners. The unfortunate result of these justifiable restrictions is that very few new propagules can be produced every year for the purpose of rebuilding the population. Serianthes nelsonii is found on two small islands in the Mariana Island Archipelago, and the population has declined to one individual on one of those islands. The recovery plan for this species calls for the propagation of more than 4,000 transplants for out-planting into several population sties. Recent propagation research conducted at the University of Guam has opened up new protocols that may greatly expand the number of propagules that can be produced every year in support of these goals. The results were published in the current issue of the journal Tropical Conservation Science. "The most successful propagation techniques vary from species to species," said author Thomas Marler. "This is especially true for woody tree species, and dedicated propagation trials are needed for each species." The new knowledge allows conservation nurseries to capitalize on the fact that specimens growing in a nursery can be used as a source for an unrestricted number of new propagules. Marler also illuminates an approach that can exploit the fresh stem tissue that is dislodged during tropical cyclones. Indeed, the western Pacific Ocean has the distinction of being the most active tropical cyclone region globally. These violent storms defoliate and dislodge branches, leaving a pulse of green litter on the forest floor. The green stem tissue found among the copious amounts of leaf litter immediately following one these storms would not fall under the permitting restrictions of how many cuttings can be taken from the trees. Conservation nurseries may maintain a collection of container-grown plants throughout each annual tropical cyclone season, ready to serve as rootstocks for the creation of grafted plants using suitable green stem tissue collected from the forest floor following a tropical cyclone. The case study is an example of how non-destructive horticulture research can be implemented on endangered species nursery plants as a means of improving species recovery protocols. Conservation funding agencies would benefit from contracting competent horticultural researchers to manage conservation nurseries. More information: Thomas E. Marler, Asexual Reproduction to Propel Recovery Efforts of the Critically Endangered Håyun Lågu Tree (Merr.), Tropical Conservation Science (2017). DOI: 10.1177/1940082917697707


Volcanically active islands abound in the tropical Pacific and harbor complex coral communities. Whereas lava streams and deep ash deposits are well-known to devastate coral communities through burial and smothering, little is known about the effect of moderate amounts of small particulate ash deposits on reef communities. Volcanic ash contains a diversity of chemical compounds that can induce nutrient enrichments triggering changes in benthic composition. Two independently collected data sets on the marine benthos of the pristine and remote reefs around Pagan Island, Northern Mariana Islands, reveal a sudden critical transition to cyanobacteria-dominated communities in 2009-2010, which coincides with a period of continuous volcanic ash eruptions. Concurrently, localized outbreaks of the coral-killing cyanobacteriosponge Terpios hoshinota displayed a remarkable symbiosis with filamentous cyanobacteria, which supported the rapid overgrowth of massive coral colonies and allowed the sponge to colonize substrate types from which it has not been documented before. The chemical composition of tephra from Pagan indicates that the outbreak of nuisance species on its reefs might represent an early succession stage of iron enrichment (a.k.a. "black reefs") similar to that caused by anthropogenic debris like ship wrecks or natural events like particulate deposition from wildfire smoke plumes or desert dust storms. Once Pagan's volcanic activity ceased in 2011, the cyanobacterial bloom disappeared. Another group of well-known nuisance algae in the tropical Pacific, the pelagophytes, did not reach bloom densities during this period of ash eruptions but new species records for the Northern Mariana Islands were documented. These field observations indicate that the study of population dynamics of pristine coral communities can advance our understanding of the resilience of tropical reef systems to natural and anthropogenic disturbances. © 2012 Tom Schils.


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: RESEARCH INFRASTRUCTURE IMPROV | Award Amount: 403.56K | Year: 2012

The University of Guam (UOG) will coordinate a Region-wide planning effort that will include members of the U.S. Affiliated Pacific-territories of Guam, American Samoa, Northern Mariana Islands, and the U.S. freely associated states of Federated States of Micronesia, Republic of the Marshall Islands, and Republic of Palau. By developing a science and technology (S&T) infrastructure, Guam and other U.S. Pacific Islands, will be able to address current economic and environmental challenges. The UOG is developing a plan to address education reform and research infrastructure improvement, both of which will impact and improve the Islands S&T workforce. Within that plan, this project will support a regional planning effort to: (i) develop a priority list of coastal and marine research issues to be addressed through a Guam led EPSCoR RII Track I proposal; (ii) develop a second level list of scientific issues to be vetted by the Pacific Region Science, Technology, Engineering and Mathematics (PacSTEM) Coalition for inclusion in the long-term PacSTEM S&T Plan; and (iii) partner with regional STEM education and outreach initiatives to add contemporary sustainability content and workforce development strategies to existing programs, and establish new certificates and AAS programs in coastal and marine sciences. The PacSTEM S&T Plan will determine the future science and engineering thrusts for Guam and the region in the years ahead and will play a critical role in establishing and implementing a long-term S&T framework.

Intellectual Merit: The U.S. island associated states and territories of the Western Pacific are challenged by the extreme effects of climate change, population growth on Guam, and bio-security risks occasioned by these significant changes. Island sustainability is therefore a major regional and economic issue. UOG has scientific focus on marine resources, from ridges to reefs, and is an emerging university in the field for interdisciplinary, collaborative scientific research. By organizing S&T capacity-building around the coastal and marine research theme, popular and economic support will be generated within the community. It will also create lasting STEM career opportunities.

Broader Impacts: This project has a high potential for broader impacts in the Western Pacific U.S. territories and affiliated states. This region is isolated, the infrastructure is underdeveloped, and the population is largely underrepresented and underserved in STEM. This project will allow UOG to lead the development of a regional S&T plan and develop a full proposal to improve the research infrastructure. These efforts will have significant impacts on Under Represented Minority (URM) groups, including Pacific Islanders. The proposal includes coordination between UOG and community colleges and other educational institutions on Guam and the partner islands.


Grant
Agency: NSF | Branch: Cooperative Agreement | Program: | Phase: RESEARCH INFRASTRUCTURE IMPROV | Award Amount: 4.06M | Year: 2015

Non-technical Description

The University of Guam (UOG) will establish the Guam Ecosystems Collaboratorium (GEC) to coordinate research in coral and marine ecology. The project will leverage Guam?s unique marine biodiversity to enhance research and education capacity while improving understanding of how coral reefs respond to environmental stress and climate change. The GEC will establish collaborations with leading universities and researchers from around the US and globally to initiate a research and education program at UOG focusing on coral reef ecology and marine biodiversity. The project will provide mechanisms for collaborative visits, exchange of doctoral students, and virtual collaborations. Cyberinfrastructure (CI) enhancements will support a repository for marine biodiversity which will serve as a global resource and establish Guam as a destination for marine ecosystems research.

Technical Description

The GEC will use RNA sequencing analysis (RNA-seq) and single nucleotide polymorphisms (SNPs) to examine genetically based stress responses in organisms found in coral reefs around Guam. A repository for biological samples and genomic and transcriptomic data will be established and connected globally via an upgraded internet connection (500 Mbps). A sensor network will be established in Pago Bay to measure environmental conditions such as temperature, salinity, and turbidity for correlating with physiological responses of corals to environmental stressors. Existing expertise in coral reef ecology and marine biology will be enhanced through new faculty hires and collaborations with researchers from other institutions. Agreements with other universities will allow the shared training of doctoral students. Research experiences will be provided for undergraduate students and teachers and the program would support a citizen science project for Pago Bay synergistic with the coral ecology research.


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: | Award Amount: 59.88K | Year: 2015

Limestone provides 25 percent of the worlds population with drinking water and contains more than 50 percent of the worlds known hydrocarbon reserves. Limestones high solubility allows for the formation of caves that control the flow of water and hydrocarbons below-ground. Understanding the processes that contribute to the formation of caves is thus necessary for improved characterization of water and hydrocarbon resources. In carbonate platform environments where limestones form (e.g. Bahamas, Yucatan and Florida), zones of unsaturated rock (vadose zone) that exceed 60 m in thickness have been proposed to limit movement of organic carbon from soil to the water table, where oxidation to carbon dioxide (CO2) would otherwise drive corrosion of limestone bedrock. In contrast to this interpretation, cave systems occur in carbonate platforms at depths of more than 100 m below modern sea level. These caves are thought to have formed in contact with fresh groundwater at times in the past when sea level was lower than it is today. Because vadose zones would have been much thicker than 60 m when these caves formed, the geochemical processes responsible for their formation are poorly understood. In this project, the movement of dissolved organic carbon (DOC) and CO2 gas to the water table via vadose zone fast flow routes is hypothesized to provide a mechanism for corroding limestone and create caves beneath thick vadose zones. This hypothesis will be tested on the island of Guam, where tectonic uplift has created vadose zones that are up to 180 m in thickness. Cave formation by CO2 that is produced by biological processes in the deep vadose zone runs contrary to the paradigm that caves in carbonate platforms form as a result of mixing waters of different chemical composition. Concepts explored by this proposal thus have potential to transform understanding of the geomorphology and biogeochemistry of the vadose zone by challenging canonical views that mixing dissolution is the principal agent of dissolution and cave formation in carbonate platform landscapes. This project supports STEM education via the training of two PhD students, providing research opportunities for three undergraduate students as well as developing lesson plans about carbonate aquifers for K-12 teachers and hands-on activities for university-led community outreach programs.

The hypothesis that subsoil respiration of CO2, rather than mixing, dominates dissolution in eogenetic limestone will be tested by collecting vadose gases, infiltration and water at water tables on the island of Guam. Uncased monitoring wells provide access for sampling vadose gases and the aquifer. Air-filled caves allow infiltrating recharge and gases to be collected throughout the vadose zone. Sampling before and after a large rain event will test the influence of fast-flow routes on dissolution. DOC in water samples will indicate whether DOC is transported to the water table and thus whether its oxidation could result in dissolution. CO2 profiles through the vadose zone will be used to determine the depths at which CO2 gas is produced. The overarching hypothesis tested here predicts production of CO2 in the vadose zone and at the water table by oxidation of DOC. CO2 and oxygen concentrations will be used together to determine 1) if vadose zone CO2 is produced by respiration or is degassed from recharging water and 2) if CO2 has been lost to the atmosphere by diffusion (typical of soils and a possible tracer of soil respiration). Dissolution of limestone will be traced using Strontium (Sr) isotopes; Guam was selected for this study because differences in the age of limestone that comprises the vadose and phreatic zone allow use of Sr isotope ratios to discriminate between dissolution in the phreatic zone from dissolution that occurs in the vadose zone followed by transport of solutes into the aquifer.


Grant
Agency: NSF | Branch: Continuing grant | Program: | Phase: POP & COMMUNITY ECOL PROG | Award Amount: 252.11K | Year: 2013

Fruit-eating vertebrates have experienced steep declines in abundance and diversity in many of the tropical forests in Asia, Africa, and South America. Many of the tropical trees that need high light to grow from seeds to adults depend largely on these vertebrates to carry their seeds to new openings, or gaps, in the forest created by treefalls. This project will investigate whether the disappearance of fruit-eating vertebrates is reducing the abundance of these trees and causing forest gaps to persist and accumulate. To test this, researchers will compare forests on the island of Guam, which has lost nearly all its fruit-eating vertebrates due to the introduction of a predatory snake, and on three nearby islands that retain native, fruit-eating, forest birds and, in one case, a native, fruit-eating bat. Studies will measure the dynamics of forest gaps on the islands, compare the light requirements of 16 common tree species, and test the effects of experimentally preventing dispersal of seeds on islands that do have birds.

This research will directly aid state and federal agencies to manage and restore tropical forests on Guam. Results should also be of use to managers of other tropical forests, since many pioneer species in the tropics are dispersed by vertebrates, and enlarge our understanding of the potential environmental consequences of introducing species to new areas. The project will provide scientific training for Pacific Islanders and run a special, three-week course in island ecology for students from local colleges.

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